Nortrac 35XT Owner's Manual page 51

2.16.1.5 Hydraulic Steering System Faults and Troubleshooting
Table 2-6 Hydraulic Steering System Faults and Troubleshooting
Fault
1. Oil leak.
2. Heavy steering.
3. Steering fails.
4. Power steering fails..
Maintenance Instructions
Causes
(1) Rubber O-rings at various pipe joints are
damaged or loose.
(2) O-rings in hydraulic steering gear valve
body, stator and rear cover are damaged.
(3) The O-ring at the axle journal is damaged.
(4) The bolts at the joint of the steering rack or
the hub subassembly have loosened.
(1) The oil supply to the gear oil pump is
insufficient, or the gear oil pump leaks inside or
the filter screen in the steering oil tank is
blocked. The steering is light at low speed and
heavy high at speed.
(2) Erratic steering cylinder movement when
the steering wheel is turned.
(3) The oil level in the steering oil cylinder is
too low.
(4) The spring tension in the relief valve has
weakened, or the steel ball is not seated
correctly. With a light load the steering is light
but the steering becomes heavier as the load
increases.
(5) Oil viscosity is too thick.
(6) Steel ball check valve in the valve body has
failed. The steering is heavy when turning
slowly or weak when turning sharply
(7) Oil leakage from the steering system, both
inside and outside.
(1) The king pin is broken or deformed.
(2) Rotor and linkage shafts are improperly
mounted.
(3) Steering cylinder or piston seal ring is
damaged.
(1) The clearance between the rotor and the
stator on the pump is too large.
(2) During power steering, the driver cannot
feel the endpoints of the extreme steering
positions. During manual steering, the steering
wheel turns but the steering cylinder does not
move.
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Troubleshooting
(1) Replace the O-ring or
tighten the fitting.
(2) Clean or replace the O- ring.
(3) Replace the O- ring.
(4) Tighten the bolts.
(1) Check the gear oil pump.
Clean the filter screen.
(2) Discharge the air from the
system and check whether there
is air or an air leak in the oil
suction pipe.
(3) Fill oil to specified height,
clean the relief valve and adjust
the spring pressure in the relief
valve.
(4) Replace defective relief
valve components.
(5) Drain oil and replace with
the specified oil.
(6) Replace valve.
(7) Troubleshoot to find the
location of the oil leak and
repair or replace leaking
components.
(1) Replace the king pin.
(2) Refit and realign.
(3) Replace the piston or the
seal ring.
(1) Replace the pump.
(2) Replace the seal ring on the
piston.